Another explanation for the low allergy rate in the rural Alpine foothills

Abstract

A low allergy rate in coal and wood heated homes has been described in the small villages in the Alpine foothills and subsequently found to be associated with the farming environment. This was interpreted within the framework of the hygiene hypothesis but there are also alternative explanations. Lower air pollution could be one reason, which is, however, unlikely since the differences between the Bavarian countryside and the Munich municipal area were only weak. There could be genetic differences between the urban and rural population by previous isolation or by self-selection. The potential drop-out of allergy genes, however, will also not explain the absent increase of allergies in two generations. More likely, other lifestyle factors are important. Dietary habits are different in farmers and a less frequent vitamin D supplementation of newborns (otherwise expected to be allergy promoting) has been shown recently. The underlying cause for the "non-allergic farm child" remains speculative until the transfer of any farm-associated factor is leading to a similar risk reduction in the general population.

Exposure to excessive oral vitamin D in youth: a risk factor for celiac disease in later life?

“…Wjst found that low levels of allergies among those in isolated rural communities in Bavaria could be explained by low levels of oral vitamin D consumption in those same communities [37]. In separate research Wjst provided evidence that allergic diseases were rare before the introduction of vitamin D supplementation and suggested that oral vitamin D is the key factor in the allergy pandemic that has engulfed the civilized world [38].…”

Nonclassical Vitamin D Actions

“…He argues that the increase in allergies in Bavaria after 1960 coincided with vitamin D supplementation intervention programs to prevent rickets in childhood. Moreover, both, adherence to these programs and prevalence of allergies in children seem to be lower in farming communities in Bavaria [ 34 ]. The farm protection is observed mainly during the first year of life [ 35 ], when vitamin D supplementation is also recommended.…”

Associação da Vitamina D com alergias alimentares

“…Estudos observacionais que examinaram os efeitos do aumento dos níveis de vitamina D na dieta através da suplementação durante infância sugerem um aumento da taxa de sensibilização e alergia, porém isto acontece quando a administração é realizada numa solução solúvel em água. Estudos ecológicos sugerem que a prevalência de alergia está ligada a práticas dietéticas regionais e/ou exposição à radiação UVB e às suas consequências sobre a síntese de vitamina D. (33,34) Variações nos níveis da vitamina D podem estar implicadas no desenvolvimento de alergias alimentares como a alergia à proteína do leite de vaca (APLV). O National Health and Nutrition Survey (NHANES), realizado em 2005-2006, mostrou que essa deficiência vitamínica foi associada a maiores níveis de imunoglobulina E (IgE) e, consequentemente, à sensibilização alérgica à alimentos e ao ambiente em crianças e idosos.…”